Combustor cap mounting structure for a turbine engine

ABSTRACT

A mounting structure for mounting a combustor cap in a combustor of a turbine engine includes support struts that are connected between the combustor cap and a concentric combustor cap barrel flange. The support struts may have an airfoil shape to minimize wakes created in a flow of compressed air that is passing over the support struts. Also, the support struts may have an interior passageway that allows a portion of the compressed air to flow though the support strut. The flow of air passing through the support struts may also pass through corresponding vent apertures in the combustor cap barrel flange so that the flow of air passing through the support struts is delivered into a space between the exterior of the combustor cap barrel flange and a forward casing of the combustor.

BACKGROUND OF THE INVENTION

A combustor for a turbine engine used in the power generation industrycan include a combustor cap that is mounted adjacent a forward end ofthe combustor. A plurality of fuel nozzles are typically mounted to anend cover and pass through the combustor cap. Compressed air flowsaround the exterior periphery of the combustor cap, makes a 180° turn,and then flows through the fuel nozzles, where the air is mixed withfuel. The air-fuel mixture is then ignited downstream from the combustorcap.

FIGS. 1 and 2 illustrate a typical background art combustor cap assemblymounted in a combustor. As illustrated in these Figures, a combustor cap110 having openings 112 to receive a plurality of fuel nozzles ismounted to a combustor cap barrel flange 118 by a plurality of A-framespacers 116. The A-frame spacers 116 are typically formed from flatmetal strips. Center portions of the A-frame spacers are mounted to theinner circumference of the combustor cap barrel flange 118, and ends ofthe A-frame spacers 116 are attached to the outer circumference 114 ofthe combustor cap 110. The combustor cap barrel flange 118 includes aprotruding flange 120. The protruding flange 120 is mounted between aflange 106 of an outer casing 105 and a flange 132 of a forward casing130.

A flow sleeve 102 is positioned inside the outer casing 106. A combustorliner 104 is mounted concentrically inside the flow sleeve 102. Aforward end of the combustor liner 104 engages a hula seal 117 on theexterior circumference 114 of the combustor cap 110. A flow ofcompressed air from the compressor section of the turbine engine flowsthrough the annular space 103 between the flow sleeve 102 and thecombustor liner 104, as illustrated by the arrows appearing in FIG. 1.This flow of compressed air also flows through the annular space betweenthe outer circumference 114 of the combustor cap 110 and the innercircumference of the combustor cap barrel flange 118. Because theA-frame spacers 116 are positioned between the outer circumference 114of the combustor cap 110 and the inner circumference of the combustorcap barrel flange 118, the A-frame spacers 116 tend to impede and/ordisrupt the flow of compressed air, resulting in flow losses andseparation.

In addition, the combustor cap design illustrated in FIG. 1 can resultin a step located between the outer circumferential surface of thecombustor cap barrel flange 118 and the inner circumferential surface ofthe forward casing 130. This step can cause disturbances in the flow ofcompressed air and a low pressure cavity 133 in the volume between theouter circumferential surface of the combustor cap barrel flange 118 andthe inner circumferential surface of the forward casing 130. In designswhere fuel is introduced through a fuel peg 135 located downstream fromthe combustor cap, such as with a quaternary fuel circuit, thedisturbances caused by this step can provide a path for fuel to migrateupstream from the fuel peg 135. Other obstacles in the compressed airflow path, such as cross fire tubes, can also cause fuel to migrateupstream. If the fuel enters the low pressure cavity 133 in the volumebetween the outer circumferential surface of the combustor cap barrelflange 118 and the inner circumferential surface of the forward casing130, it can lead to a flame holding event. All of which is undesirable.

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, the invention may be embodied in a combustor cap assemblyfor a turbine engine that includes a generally cylindrical combustor capconfigured to receive at least one fuel nozzle, a generally cylindricalcombustor cap barrel flange that surrounds an outer circumference of thecombustor cap, and a plurality of support struts that mount thecombustor cap to the combustor cap barrel flange. The support strutsextend between the outer circumference of the combustor cap and an innercircumference of the combustor cap barrel flange. An interior passagewayextends through an interior of each support strut.

In another aspect, the invention may be embodied in a support strut thatis configured to mount a combustor cap to a combustor cap barrel flangeof a combustor of a turbine engine. The support strut includes a mainbody having an inner end that is configured to be attached to the outercircumference of a combustor cap and an outer end that is configured tobe attached to an inner circumference of a combustor cap barrel flange.Also, an interior passageway extends through the main body between anentrance aperture and an exit aperture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a background art mounting structure for mountinga combustor cap in a combustor of a turbine engine;

FIG. 2 is a diagram illustrating how a background art combustor cap ismounted to a combustor cap barrel flange;

FIG. 3 is a perspective view of a first embodiment of a support strutthat is used to mount a combustor cap to a combustor cap barrel flange;

FIG. 4 is a cross-sectional view of a support strut mounted to acombustor cap barrel flange;

FIG. 5 is a diagram illustrating how support struts as illustrated inFIGS. 3 and 4 are used to mount a combustor cap to a combustor capbarrel flange;

FIG. 6 is a diagram, illustrating how a combustor cap and combustor capbarrel flange assembly that includes support struts as illustrated inFIGS. 3 and 4 is mounted to a combustor of a turbine engine;

FIG. 7 is a cross-sectional view of an alternate embodiment of a supportstrut that can be used to mount a combustor cap to a combustor capbarrel flange; and

FIG. 8 is a diagram, illustrating how another embodiment of a combustorcap and combustor cap barrel flange assembly that includes supportstruts as illustrated in FIGS. 3 and 4 is mounted to a combustor of aturbine engine.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 3 and 4 illustrate a support strut 160 which can be used to mounta combustor cap to a combustor cap barrel flange. The support strut 160replaces the A-frame spacers 116 used for this purpose in the backgroundart combustor cap assembly illustrated in FIGS. 1 and 2. The supportstrut 160 has an airfoil shape, with a rounded leading edge 161 and atapered trailing edge 163. In addition, an interior passageway extendsthrough the interior of the support strut 160 between an entranceaperture 162 and an exit aperture 164.

FIG. 4, which is a cross-sectional view of a support strut 160 attachedto a combustor cap barrel flange 150, illustrates that the inner end 166and outer end 168 of the support strut 160 are substantially parallel toone another. In alternate embodiment, however, the inner and outer endscould be angled relative to one another. In some embodiments, theleading edge 161 and trailing edge 163 of each support strut 160 may beangled with respect to the inner end 166 and outer end 168. FIG. 4 alsoillustrates that an interior passageway 165 passes between an entranceaperture 162 and an exit aperture 164 of the support strut. The exitaperture 164 is in communication with a vent aperture 152 in thecombustor cap barrel flange 150. As a result, air entering the entranceaperture 162, flowing through the interior passageway 165 and exitingthe exit aperture 164 can pass through the vent aperture 164 of thecombustor cap barrel flange 150.

FIG. 5 illustrates how a plurality of support struts 160 are used tomount a combustor cap 110 to a combustor cap barrel flange 150. Innerends 166 of each support strut 160 are mounted to an exteriorcircumference 114 of the combustor cap 110. Outer ends 168 of eachsupport strut 160 are mounted to an interior circumferential surface 154of the combustor cap barrel flange 150. In some embodiments, the innerand outer ends of the support struts 160 may be integral to thecombustor cap 110 and combustor cap barrel flange 150, respectively. Inalternate embodiments, additional structure may be provided to helpattach the support struts 160 to one or both of the combustor cap 110and combustor cap barrel flange 150. FIG. 5 presents a view which showsthe leading edges of the support struts 160. As a result, one can seethe entrance apertures 162 on the leading edges of the support struts160.

FIG. 6 illustrates a side view of the combustor assembly, which showshow the support struts 160 are mounted between the combustor cap 110 andthe combustor cap barrel flange 150. FIG. 6 also illustrates that theleading edge 161 of the support struts are positioned so that the flowof compressed air exiting the annular space 103 between the flow sleeve102 and the combustor liner 104 impinges directly on the leading edges161 of the support struts 160. As a result, a portion of the compressedair flows into the entrance aperture 162, through the interiorpassageway 165, out the exit aperture 164 of the support strut 160, andthen through the vent aperture 152 in the combustor cap barrel flange150, as illustrated by the arrows in FIG. 6. The flow of air passingthrough the interior of the support struts 160 is delivered into the lowpressure cavity 133 between the outer circumferential surface of thecombustor cap barrel flange 150 and the inner circumferential surface ofthe forward casing 130. Thus, the flow of air continuously purges thelow pressure cavity 133 that existed in the background art design.

The airfoil shape of the support struts 160 also help to minimize anyflow losses that result from the flow of compressed air impinging on thestructure used to attach the combustor cap 110 to the combustor capbarrel flange 150. Another benefit of the airfoil shape is that it helpsto minimize wakes if the flow of compressed air has a tangentialcomponent (swirl). If the air coming from the annular space 103 isswirling, the background art A-frames tended to cause a large wake, asthey essentially act like flat plates with an angle of attack. Incontrast, when airfoil shapes are used for the support struts the airwill tend to stay attached to the airfoil in moderate angles of attack(swirl) thereby minimizing wakes or flow deficits from the structure.

FIG. 7 illustrates an alternate embodiment of a support strut 190 thatcan be used to attach a combustor cap 110 to a combustor cap barrelflange 150. In this embodiment, the interior passageway 175 makes asmooth curve between the entrance aperture 162 on the leading edge 161of the support strut and the exit aperture 164 that is in communicationwith the vent aperture 152 in the combustor cap barrel flange 150. Thesmoothly curved interior passageway 175 also serves to minimize flowlosses and maximize the flow of air that is used to purge the deadcavity.

In alternate embodiments, the entrance aperture of a support strut couldbe located on portions of the sidewall of the support strut other thanthe leading edge. For example, the entrance aperture could be located ona portion of the sidewall between the leading and trailing edges.

In still other embodiments, multiple entrance apertures could beprovided on multiple portions of the sidewall of the support strut. Forexample, multiple entrance apertures could be formed on the leading edge161 of a support strut. In some embodiments, all of the entranceapertures would lead to the same interior passageway. In alternateembodiments, each entrance aperture could lead to a separate interiorpassageway.

Also, in the embodiments described above, the exit aperture is locatedon the outer end of the support struts. In alternate embodiments, theexit aperture could be located in different locations. Also, multipleexit apertures could be provided.

In an embodiment of a support strut having multiple entrance aperturesand/or multiple exit apertures, multiple interior passageways may beprovided.

In the embodiments described above, the support struts have across-sectional shape with a rounded leading edge and a tapered trailingedge. In alternate embodiments, the support strut could have alternatecross-sectional shapes. For example, the support struts could have arectangular cross-sectional shape, with or without rounded edges.Alternatively, the support struts could have a circular or ovalcross-sectional shape. Still other cross-sectional shapes are alsopossible, depending on design considerations.

In the embodiments described above, the leading and trailing edges ofthe support struts were angled with respect to the inner and outer ends.In alternate embodiments, the inner and outer ends could form rightangles with the leading and trailing edges of the support struts. Also,in alternate embodiments, the leading and trailing edges may be angledsuch that the inner ends of the support struts extend further rearwardthan the outer ends.

FIG. 8 illustrates another embodiment of a combustor assembly wheresupport struts 160 are mounted between a combustor cap 110 and acombustor cap barrel flange 150. In this embodiment, a slot 137 is cutin the forward casing 130, and the combustor cap barrel flange 150 ismounted in the slot 137. A cavity 139 is formed between the innercircumference of the slot 137 and the outer circumference of thecombustor cap barrel flange 150. A portion of the compressed air exitingthe annular space 103 flows into the entrance aperture of the supportstrut 160, through the interior passageway, out the exit aperture of thesupport strut 160, and then through a vent aperture in the combustor capbarrel flange 150 and into the cavity 139, as illustrated by the arrowsin FIG. 6. Thus, a flow of air continuously purges the cavity 139. Theflow of air exiting the cavity 139 through the gap 151 prevents fueldelivered from a downstream fuel peg 135 from migrating upstream intothe location adjacent the trailing edges of the support struts 160.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements which are encompassed withinthe spirit and scope of the appended claims.

What is claimed is:
 1. A combustor cap assembly for a turbine engine,comprising: a generally cylindrical combustor cap configured to receiveat least one fuel nozzle; a generally cylindrical combustor cap barrelflange that surrounds an outer circumference of the combustor cap; and aplurality of support struts that mount the combustor cap to thecombustor cap barrel flange and which extend between the outercircumference of the combustor cap and an inner circumference of thecombustor cap barrel flange, wherein an interior passageway extendsthrough an interior of each support strut.
 2. The combustor cap assemblyof claim 1, wherein vent apertures are formed in the combustor capbarrel flange at locations corresponding to where the support struts areattached to the combustor cap barrel flange, and wherein each ventaperture operatively communicates with the interior passageway of acorresponding support strut.
 3. The combustor cap assembly of claim 2,wherein the interior passageway in each support strut extends between anentrance aperture located on a side surface of the support strut and anexit aperture that is formed on a portion of the support strut thatabuts the combustor cap barrel flange.
 4. The combustor cap assembly ofclaim 3, wherein the entrance aperture of each support strut is locatedon a leading edge portion of the support strut which is impacted by aflow of compressed air.
 5. The combustor cap assembly of claim 3,wherein the support struts are mounted to the combustor cap barrelflange such that a flow of air can pass from the entrance aperture ofeach support strut, through the interior passageway, out the exitaperture of the support strut and through a corresponding vent apertureof the combustor cap barrel flange to a location adjacent an exteriorcircumference of the combustor cap barrel flange.
 6. The combustor capassembly of claim 1, wherein each support strut has an airfoil shapewith a rounded leading edge and a tapered trailing edge.
 7. Thecombustor cap assembly of claim 1, wherein a leading edge of eachsupport strut is angled with respect to the outer circumference of thecombustor cap and the inner circumference of the combustor cap barrelflange such that the portion of the leading edge that is coupled to thecombustor cap is located further forward than the portion of the leadingedge that is coupled to the combustor cap barrel flange.
 8. Thecombustor cap assembly of claim 7, wherein each support strut has anairfoil shape with a rounded leading edge and a tapered trailing edge.9. A support strut configured to mount a combustor cap to a combustorcap barrel flange of a combustor of a turbine engine, comprising: a mainbody having an inner end that is configured to be attached to the outercircumference of a combustor cap and an outer end that is configured tobe attached to an inner circumference of a combustor cap barrel flange;and an interior passageway that extends through the main body between anentrance aperture and an exit aperture.
 10. The support strut of claim9, wherein the entrance aperture is located on a sidewall of the mainbody and the exit aperture is located on the outer end of the supportstrut.
 11. The support strut of claim 10, wherein the entrance apertureis located on a leading edge of the main body.
 12. The support strut ofclaim 9, wherein the main body has an airfoil shape with a roundedleading edge and a tapered trailing edge.
 13. The support strut of claim9, wherein the inner and outer ends are substantially parallel to oneanother, wherein a leading edge of the main body forms an oblique anglewith the inner end, and wherein a trailing edge of the main body formsan acute angle with the inner end.
 14. The support strut of claim 13,wherein the main body has an airfoil shape with a rounded leading edgeand a tapered trailing edge.
 15. The support strut of claim 14, whereinthe entrance aperture is located on the leading edge of the main bodyand the exit aperture is located on the outer end of the main body.